I've tried to use this command :/entitydata @e[r=2,type=Zombie] {Riding:{id:Pig}}.
Theoretically, it should change the zombie and put it on a pig, so it should ride it, but it doesn't work, nothing changes.
Relogging doesn't change the result.
Linked issues
is duplicated by 7
Comments 4
Confirmed. The game reports having changed the tag, but it isn't saved; possibly because it is an incomplete entity.
Please do not report issues related to NBT tags as bugs. If changing NBT via commands does not have the expected effect, that's always considered "working as intended".
Similar to trying this thing on a chicken:
/entitydata @e[type=Chicken] {IsChickenJockey:1}
But I think it Works as Intended - you can't summon new entity by changing data tags of another entity. You are just trying to attach existing entity to something what doesn't exist...